It has heretofore been proposed to use "bumper" type feeds in the magazines of folding paper box machines for assuring that only the leading edge of the lowermost blank in a stack of identical, flat box blanks will be advanced through the gateway of the magazine guage and along the horizontal paper line of the machine.
One type of bumper feed is disclosed in U.S. Pat. No. 3,406,963 to Goss of Oct. 22, 1968, wherein the upper reaches of a plurality of endless carrier belts advance under the lower surface of the lowermost blank in a stack and are liftable into contact with that surface to advance the lowermost blank by means of cams.
In another type of bumper feed disclosed in U.S. Pat. No. 3,612,512 to Lang of Oct. 12, 1971, the lifting members are between the carrier belts and instead of raising the belts into contact with the lower blank they lift the lower blank out of contact with the belts for controlling feed.
The bumper feed of this invention is timed and of the Lang type in that elongated lifter bars mounted in the space between feed belts, are raised and lowered to conrol the feed of each successive lowermost blank out of the gateway at the bottom of the stack. Such a bumper feed was made and sold by the International Paper Box Machine Company of Nashua, New Hampshire in February 1971 on a straight line folder-gluer.